(A) Field of the Invention
The present invention is related to an expansion card fixture, more specifically, to an expansion card fixture for wireless data transmission.
(B) Description of Related Art
A wireless LAN (Local Area Network), instead of a wiring network, is widely used to internally transmit digital data in a company. Some buildings such as international airports, hotels and coffee shops are also constructing wireless LANs that provide communication services to customers. Users can utilize a personal computer or a PDA (personal Digital Assistant) having a wireless network card to link to the nearest access point. Therefore, in spite of e-mails, business status checking and internet games, the accesses and operations of network are without time-lag and distance. Gateways and routers in addition to access points are common wireless transmission apparatuses in a wireless LAN.
An expansion card is implemented as a peripheral of an apparatus such as a computer dictionary, PDA and the like. A PCMCIA (Personal Computer Memory Card International Association) card is widely used in a computer for linkage to a network. When a PCMCIA card is used for wireless transmission, EMI (Electromagnetic Interference) and environment testing problems become noticeable.
Traditionally, the fixing of a PCMCIA card of a wireless gateway is shown in FIG. 1(a): a conductive shielding gasket 13 is adhered to a PCB (Printed Circuit Board) 11, and then plastic tenons 14 are added to and covered by a metal structure 15. The conductive shielding gasket 13 is for grounding to prevent EMI occurring on the PCMCIA card used in a wireless gateway. The PCB 11 contains a socket 12 for insertion of one end of the PCMCIA card, and the metal structure 15 is for fixing the other end of the PCMCIA card. In FIG. 1(b), a PCMCIA card 16 is inserted between the socket 12 and the metal structure 15, and a sticker 17 is adhered to both the socket 12 and the PCMCIA card 16 afterwards to avoid their relative movement.
The above-mentioned fixing procedure of the PCMCIA card 16 has to sequentially set the conductive shielding gasket 13, the plastic tenons 14, and the metal structure 15, to insert the PCMCIA card 16 and to adhere a sticker 17. The procedure not only is complicated but takes more time, and is not convenient for on-line rework. As to reliability, the grounding performance of the conductive shielding gasket 13 is inconsistent and is unable to completely avoid EMI occurrence. Because the PCMCIA card 16 is not rigidly fixed in the metal structure 15, the worse grounding reliability often affects the environment testing performance. Furthermore, many components such as the conductive shielding gasket 13, the plastic tenons 14, the metal structure 15 and the sticker 17 are required, resulting in the puzzle to the management and purchase of such parts.
The object of the present invention is to provide an expansion card fixture for simplifying manufacturing process, enhancing reliability, diminishing the number of parts, and effectively avoiding EMI occurrence during wireless data transmission.
The expansion card of the present invention for fixing an expansion card to a PCB comprises a first plate, a second plate, a supporting member, at least one blocking plate and at least two side plates, where one end of the second plate connects to the bottom end of the first plate, and the second plate directs at an angle to the first plate. Therefore, the spring structure constituted of the first plate and the second plate can recover to the original shape. One end of the supporting member connects to the middle of the first plate to support the expansion card. The blocking plate comprises an edge plate and a top hook, the edge plate whose bottom connects to the top of the first plate being perpendicular to the second plate to prevent longitudinal movement of the expansion card. The top hook formed at the top of the edge plate protrudes from the edge plate and heads for the bottom of the first plate to prevent vertical movement of the expansion card. The two side plates individually connected to both sides of the first plate protrudes upwards from the first plate to prevent transverse movement of the expansion card.
The expansion card fixture can be fixed to a PCB by at least one fixing plug, a screw or by welding. The expansion card fixture can be formed by bending a metal plate, and thus the performance and reliability of grounding can be enhanced, i.e., EMI is decreased, by virtue of the flexibility of the metal plate.